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Thursday, January 9, 2014

Under the Electron Microscope

It may be hard to believe but the first electron microscope was developed by German physicist Hans Busch in 1926 with a prototype built by Ernst Ruska and the electrical engineer Max Knoll in 1931. In 1933 Ruska built an electron microscope (or EM) that surpassed the resolution which could be achieved with a light microscope. Yet perhaps even Ruska could not have envisioned future developments, which mean that today we can see things such as the zinc oxide particle (above) in more detail than ever before.

The difference between an EM and the microscope of old is fairly straightforward even if the science which separates them is not. An EM uses an electron beam to illuminate a specimen rather than light. As such is can make out tiny details of a given object with a significantly greater resolving power than a light microscope. The detail is greater because the wavelength is shorter: visible light photons are about 100,000 times longer than those of electrons in terms of wavelength. The picture above shows the aftermath of fayalite reacting with gaseous CO2 to form siderite, thereby capturing the CO2 in a solid, stable form

The difference in terms of our ability to enlarge something in appearance using light or electrons is extraordinary. With a light microscope the limits are reached at around 2,000 times magnification. With an electron microscope an object can be magnified up to 10 million times. Even if you are not a mathematician, the difference is staggering. This means that objects previously invisible can now be seen. Today, you can see rod-shaped E. coli bacteria nestling inside a minute pore in the leaf called a stoma above - the plant itself is a lettuce. It is almost like stepping foot on an alien planet.

EMs are used to explore and examine the ultrastructure of objects. Ultrastructure refers to the parts of an entity that cannot be seen with an optical microscope and these may include microorganisms, large molecules, crystals, cells and samples used in biopsies. In the case above, it is an advanced wound dressing based on BASF’s superabsorber technology which ensures constant moist conditions – an important prerequisite for fast wound healing. The image is captured for us as a micrograph. This is the big brother of a macrograph (or macrophotography in general) in as much as the macro magnifies what can already be seen and the macro magnifies and shows us that which cannot.

Image Credit Flickr User Engineering at CambridgeThe star shaped object visible in the center of the micrograph above is a zinc oxide crystal, which is attached to a supporting mesh made of amorphous carbon. Zinc oxide is a material widely investigated for potential applications in transistors, light emitting diodes and solar cells. This area of research focuses on finding cheap alternatives to already existing technologies. This could result in cheaper computers and smart phones, and cheap solar powered chargers for electronic appliances.

Image Credit Flickr User Carl Zeiss MicriscopyTo create a micrograph a specialized digital camera is used (or alternatively, a frame grabber). The outcome isordinarily a black and white image. These are then colorized through feature detection software or very occasionally even Photoshop! Above you can see the stamens of the meadowsweet flower as caught by an EM without any enhancement in terms of color - you can even see the pollen beginning to extrude on top of the anther. So, what you see here may not be exactly what you might encounter (color wise) if you were to do aFantastic Voyage thing but rather it is used to clarify structure. Yet feature detection software is becoming extremely sophisticated. Moreover, the aesthetic effect is phenomenal. Take a further look under the electron microscope.

Image Credit Flickr User BASFHere you can see chloroplasts which are organelles found in plant cells. They conduct photosynthesis. The plant above is, however, a weed and the little dots you can see on the chloroplasts are a herbicide which blocks one of the main enzymes used in chlorophyll biosynthesis. This puts a stop to photosynthesis which means no conversion of light to energy. Bye-bye weed.

Image Credit Flickr User BASF These are spandex fibers which have over the last five decades made sure that some items of our clothing retain their elasticity for much longer than they ordinarily would.

Image Credit Flickr User Engineering in CambridgeZinc oxide again, but this time it has clustered and is layered in to a dome. Furthermore, it has embedded itself in to a nanostructured porous substrate (a tool for cell research). This is a by-product of controlled crystallisation, created in the research for components for sustainable energy devices. James Bendall, who created this image, called it the tortoise in the hair.

Image Credit Flickr User Carl Zeiss MicroscopyWhat you can see here is the body trying to cure itself. The yellow cigar shaped objects are tuberculosis bacteria. Around it is macrophage. A macrophage is a phagocyte, and these are the cells that protect us by attempting to ingest and harmful foreign objects. The name comes from the Greek phagein – to devour and the word cyte which denotes a cell in biology.

Image Credit Flickr User BASFThe spheres you can see here are spores created by the Emericella nidulans fungus. They produce the protein hydrophobin which makes the spores waterproof. A waterproof protein could be useful…

Image Credit Flickr User BASF If you have a digital camera or a hybrid car then the chances are that the energy source used for your batteries are these – metal oxide particles with lithium ions embedded in to them. If the power for your device does not come out of a socket then the battery will have something that looks like this as its energy source.

Image Credit Flickr User BASFYou don’t need to go to LV-223 when you have these right here on Earth. This is a soybean and what you can see erupting from its surface is a fungus known as soybean rust. Huge efforts are being made to find a way to control this as, once it attacks, it can destroy up to 80 percent of a harvest.

Image Credit Flickr User BASFThis is one way. Today many soybeans are treated, like the one above. The soybean has been coated with a product that forms a protective film around it – just one tenth the thickness of a human hair. It is hoped that this treatment will stop the soybean rust from gaining a hold on this important world harvest.

Image Credit Flickr User BASFEver had tooth decay? Caries is caused by bacteria - Streptococcus mutans which converts sugar left on the surface of your teeth in to acids. That acid then attacks and destroys tooth enamel causing cavities and bills. Here the blue Streptococcus mutans is being attacked by a man made bacteria, specifically developed to attack and kill it.

Image Credit Flickr User BASFFinally, these are artificial spider’s webs. They were created using woven protein fibers and are 1,000 times thinner than a human air. It is hoped that they can help treat wounds in the future for a number of reasons. First, they are not known to cause any allergies and they are permeable by air meaning the wound can still breathe. Moreover, the body will break down the protein layer which will mean no plasters sticking to the wound when it is taken off. What goes around comes around – the ancient Greeks and Romans used spider webs to stem bleeding.